JP3986962B2 - Electrochemical device with retractable electrode - Google Patents

Abstract

Electrochemical apparatus and methods that support periodic, non-steady state, or discontinuous operation without suffering degradation of materials or loss of efficiency. The invention provides a means for positioning one or more electrodes into contact with electrolyte and means for retracting the one or more electrodes out of contact with the electrolyte. The means for positioning and means for retracting may be the same device or different devices. The means for positioning and means for retracting may be designed to provide automatic, passive, or fail-safe retraction of the electrode upon a given standby condition, such as a voltage of less than one Volt being applied between the first and second electrodes, expiration of a time period, an ozone concentration greater than a set point ozone concentration, contact pressure of less than 5 psig, and combinations thereof.

Description

  The present invention relates to an electrochemical device that enables periodic operation without causing long-term efficiency loss or material degradation, particularly in an electrocatalytic layer or coating.

  Ozone is known to be a powerful oxidizing species. A number of methods and devices have been used to generate and use ozone. However, many potential applications for ozone use do not require or utilize a continuous ozone gas stream or ozonated water stream. The generation and use of ozone in raw, discontinuous, unsteady mode, or batch mode operation can be problematic for a variety of reasons. First, because ozone is highly reactive and decomposes quickly, ozone must be generated immediately before use. For this reason, the ozone generation capacity must closely match the peak consumption rate. Second, when generating high concentrations of ozone, an electrochemical process is preferred, and it is most preferred to use a lead dioxide anode electrocatalyst.

Although lead dioxide (PbO ₂ ) is generally unstable in aqueous acid solutions, the potential-pH equilibrium diagram for 25 ° C. lead-water in FIG. 1 shows a standard on the PbO ₂ positive electrode in an electrochemical device. It has been shown that lead dioxide can be stabilized by maintaining a high positive electrode potential relative to the hydrogen electrode (SHE). Thus, instability of lead dioxide in acidic solution is easily avoided in continuous electrochemical processes. This is because a relatively high potential is continuously maintained between the positive electrode and the negative electrode. If the electrochemical process is only required periodically, the potential supplied between the positive and negative electrodes can be lowered to reduce the rate of the electrochemical process and reduce the current trickle between the electrodes. By maintaining it, lead dioxide is stabilized. Bad, continuous electrochemical processes and continuous potential are impractical for many applications such as residential or consumer products. This is because a power failure may occur or the backup battery may be exhausted. Yet another possible solution is to use platinum metal as the anode electrocatalyst, but the disadvantages of using platinum include lower ozone yields and higher costs.

  The heart of every electrochemical cell's operation is the generation of redox reactions that produce or consume electrons. These reactions occur at the electrode / solution interface and the electrode must be a good conductor. In operation, the cell is connected to an external load or external voltage source, and electrons transfer charge between the anode and cathode via an external circuit. In order to complete the electrical circuit through the cell, there must be an additional mechanism for internal charge transfer. Internal charge transfer is obtained by one or more electrolytes and corresponds to charge transfer by ionic conduction. In order to prevent internal short circuit of the cell, the electrolyte must be a poor conductor.

  The simplest electrochemical cell is composed of at least two electrodes and one or more electrolytes. The electrode from which the electrons that generate the oxidation reaction are generated is the anode. The direction of electron flow in the external circuit is always from the anode to the cathode.

  An electrochemical cell in which a chemical reaction is forced by additional AC / DC electrical energy is called an electrolysis cell. Electrochemical cells also include fuel cells that are supplied with fuel to generate DC current and batteries such as zinc / manganese dioxide.

The electrolyte may be a liquid electrolyte (water-soluble or organic solvent, and dissolved salt, acid or base), or a solid electrolyte such as a polymer-based ion exchange membrane. The polymer ion exchange membrane can be either a cation exchange membrane (proton exchange membrane, PEM, etc.) or an anion exchange membrane. The film may be a ceramic film such as yttrium stable zirconia which is an O- ² ion conductor.

However, ozone (O ₃ ) can also be generated by an electrolysis process, in which a current (usually DC) is applied between electrodes immersed in the electrolyte. The electrolyte contains water, which decomposes into the respective elemental species O ₂ and H ₂ . Under appropriate conditions, oxygen is also generated as O ₃ species. Oxygen and ozone generation at the anode can be expressed as follows.

2H ₂ O → O ₂ + 4H ⁺ + 4e ⁻
3H ₂ O → O ₃ + 6H ⁺ + 6e ⁻
Utilization of high excess potentials, such as anode potentials higher than 1.57 volts, and certain electrocatalytic materials enhance ozone formation at the expense of oxygen generation. The hydroxylation reaction generates protons and electrons that recombine at the cathode. The electrons are guided to the cathode through an external electronic circuit. Protons are transported through a solid electrolyte such as a proton exchange membrane (PEM).

  The cathodic reaction can use hydrogen formation.

2H + + 2e ⁻ → H ₂
Or, it involves the reduction of oxygen as follows.

O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O
O ₂ + 2H ⁺ 2e ⁻ → H ₂ O ₂
In order for the oxygen reduction reaction to be performed efficiently, a dedicated gas diffusion electrode is required. The presence of oxygen at the cathode suppresses the hydrogen formation reaction. Furthermore, the oxygen reaction is thermodynamically preferred over the hydrogen reaction. Thus, the reduction of oxygen to water or hydrogen peroxide reduces the overall cell voltage than is required to generate hydrogen.

  Accordingly, there is a need for an electrochemical cell and method that accommodates periodic, non-steady state, or discontinuous operation without incurring degradation of materials including electrocatalysts or reduced efficiency. These devices and methods are desirable if the operator does not need to be careful to verify the status of the power supply. Furthermore, it is desirable that these devices be capable of a large amount of repeated use in various operations and standby periods and frequencies.

The present invention comprises a cathode electrode, an anode electrode, an acidic electrolyte such as an ion exchange membrane disposed between the anode electrode and the cathode electrode, and a power source for applying a voltage between the anode electrode and the cathode electrode. An electrochemical cell comprising or including is provided. The electrochemical cell has one or more other electrocatalysts that are unstable or inactivated when the anode electrode is in the presence of a layer of lead dioxide electrocatalyst facing the acidic electrolyte or an electrolyte that does not apply voltage. And a retracting mechanism for retracting the anode electrode from an initial position where the lead dioxide electrocatalyst contacts the electrolyte to a retracted position where the lead dioxide electrocatalyst is separated from the electrolyte in response to a predetermined standby state of . Optionally, the retraction mechanism is a passive retraction mechanism such as a spring, gravity, hydraulic accumulator, air accumulator, or combinations thereof. Preferably, the lead dioxide electrocatalyst is β-lead dioxide, α-lead dioxide, or a combination thereof. In one embodiment, the acidic electrolyte is a proton exchange membrane. In another embodiment, the acidic electrolyte comprises a dissolved inorganic acid, a dissolved organic acid,
Or an aqueous solution of a mixture thereof.

One or more standby states are that the voltage applied between the first electrode and the second electrode is less than 1 volt, the cell operating time period has expired, and the ozone concentration is the set ozone concentration in the cell. The anodic oxygen / ozone generation reaction is not occurring, and no current is flowing through the cell. Further, the one or more standby states may preferably include that the contact pressure of the anode electrode with the proton exchange membrane is less than 10 psig (69 kN / m ² ). One or more generation conditions are that the voltage applied between the first electrode and the second electrode is higher than 1 volt , that a period of time has expired from the end of cell operation, and that the ozone concentration is within the cell. It is selected because it is lower than the set ozone concentration.

  Optionally, the electrochemical cell further moves the anode electrode from the retracted position to the initial position in response to one or more production conditions such that the contact pressure of the anode electrode with the electrolyte exceeds a set pressure. An actuator that moves and returns may be provided. Preferably, the retraction mechanism and the actuator are constituted by a passive device that biases the anode electrode away from the electrolyte and an active mechanism that overcomes the biasing action of the passive device in operation to move the anode electrode into contact with the electrolyte. ing. It is also preferred that the power supply supply power to the active mechanism when the active mechanism receives power from the power supply and the power supply is connected to apply a voltage between the anode and cathode electrodes. The invention is characterized in that lead dioxide maintains its activity during each cycle of power supply.

  The electrochemical device further includes a pump that delivers water to at least the anode electrode of the electrochemical cell, and the retracting means is a hydraulic actuator that is also in fluid communication with the water. Preferably, one of the electrolyte, such as an ion exchange membrane, and the electrode, most preferably the cathode, is fixed. When using lead dioxide electrocatalysts, it may be desirable to include a delead device in fluid communication with the electrochemical cell, in which case the delead device is known to bind or adsorb lead ions, particles or colloidal species. Built-in materials that are used. Such deleading material can be selected from zeolite, alumina, silica, or mixtures thereof and can be in powder or granular form.

  In a preferred embodiment, when no voltage is applied between the first electrode and the second electrode, one or more of the anode and cathode electrodes are retracted to break contact with the electrolyte. The means for retracting one or more of the anode and cathode may include a guide member for aligning the electrodes.

  Preferably, the electrochemical device further comprises means for positioning the first electrode and the second electrode in contact with the electrolyte. Preferably, the electrolyte is an ion exchange membrane, and the first electrode is coupled to the arrangement means, and an electrocatalyst is formed only on the surface of the first electrode, and is arranged so as to contact the ion exchange membrane. In one embodiment, one of the electrodes is fixed and the ion exchange membrane is secured onto the fixed electrode.

An example of the placement means is selected from hydraulic actuators, pneumatic actuators, manual mechanical means, piezoelectric means, electric motor means, or a combination thereof. Preferably, the compressive force supplied to the ion exchange membrane is 5 psig (34 kN / m ²⁾ is between ~100psig (kN / ^{m 2),} and most preferably greater than 15psig (103kN / ^{m 2).} The apparatus can be designed such that the retracting means overcomes the positioning means when the power is off, or the positioning means overcomes the retracting means when the power is on.

The present invention also relates to an electrochemical cell comprising a cathode electrode, an anode electrode, an acidic electrolyte disposed between the anode electrode and the cathode electrode, and a voltage source coupled between the anode electrode and the cathode electrode. Provides a method of generating ozone. The method includes the step of applying a voltage between the anode electrode and the cathode electrode, and first the anode electrode is moved from a retracted position away from the electrolyte,
Moving to an operating position in contact with the electrolyte and turning on the voltage source prior to or simultaneously with engagement of the anode with the electrolyte, the method further comprising immediately before or simultaneously with turning off the voltage source Retreating, and the step of breaking contact with the acidic electrolyte is included. Optionally, the step of retracting the anode electrode and disconnecting from the acidic electrolyte is performed in response to sensing one or more predetermined standby conditions. For example, one or more standby conditions are that the voltage applied between the first electrode and the second electrode is less than 1 volt, the cell operating time period has expired, and the ozone concentration is set in the cell. It is selected because it is higher than the ozone concentration, no anodic oxygen / ozone generation reaction occurs, and no current flows through the cell. Alternatively, the one or more standby conditions include the contact pressure of the anode electrode with the proton exchange membrane exceeding 10 psig (69 kN / m ² ).

In another embodiment, contact engagement of the anode electrode with the electrolyte occurs in response to sensing one or more production conditions. One or more generation conditions are that the voltage applied between the first electrode and the second electrode is higher than 1 volt , that a period of time has expired from the end of cell operation , and that the ozone concentration is within the cell. It is selected because it is lower than the set ozone concentration.

In one or more standby states, the voltage applied between the first electrode and the second electrode is less than 1 volt, the expiration of a certain period of time, and the ozone concentration is higher than the set ozone concentration in the cell The contact pressure may be selected from, but not limited to, less than 10 psig (69 N / m ² ), or a combination thereof. Further, the above-described method can also include automatically placing one or more of the first electrode and the second electrode in contact with the electrolyte when one or more production conditions are met. One or more generation conditions are that the voltage applied between the first electrode and the second electrode is higher than 1 volt , that a certain period of time has expired, and that the ozone concentration is higher than the set ozone concentration in the cell. It can be selected from low, contact pressure higher than 10 psig (69 N / m ² ), or combinations thereof.

Suitable electrolytes are polymer electrolyte membrane, the step of automatically arranged, ^preferably, compressive force of 5psig (34kN / m 2) ~100psig (689kN / m 2), and most preferably 25psi (172kN / ^{m 2} ) To press one or more of the first and second electrodes against the polymer electrolyte membrane with a compressive force of -70 psig (483 kN / m ² ). Of course, the steps of the disclosed method are generally not limited to performing the steps in a given order, but when using lead dioxide electrocatalysts, one or more production conditions may be present. When established, it is important to apply a voltage to the first and second electrodes before placing the first and second electrodes in contact with the electrolyte.

  The electrochemical cell having the above-described structure further includes a mechanism for retracting the anode electrode and disconnecting the electrolyte in response to the absence of current passing through the electrochemical cell. It can also be a feature. Instead, an electrochemical cell having the above-described structure further overcomes the biasing action of the passive device when the apparatus is further in operation with a passive device that biases the anode electrode away from the electrolyte, An active mechanism for moving the anode electrode to contact the electrolyte may be provided. Further optionally, the active mechanism is adapted to be activated when a power source is connected and a voltage is applied between the electrodes. In yet another alternative, an electrochemical cell having the above-described structure causes the apparatus to wait for the cell by further retracting the anode electrode, disconnecting the electrolyte, and interrupting the circuit incorporating the cell. It can also be characterized by having a mechanism for making the state.

In order that the above-cited features and advantages of the present invention may be understood in detail, a more particular description of the invention briefly described above will be made with reference to the embodiments illustrated in the accompanying drawings. . It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the invention and that the invention allows other equally valid embodiments and therefore should not be considered as limiting its scope. Keep it.

  The present invention provides an electrochemical cell and method that accommodates periodic, non-steady state, or non-continuous operation without incurring degradation or reduced efficiency of the material containing the electrocatalyst. In these devices and methods, the operator does not have to be careful to verify that the potential between the positive and negative electrodes, also called cell voltage, is continuously applied to the cell. In addition, these devices and methods support a large number of repetitive “on” / “off” cycles in various operations and standby periods and frequencies.

  The basic structural unit of an electrochemical device is an electrochemical cell. That is, an electrochemical device can be a single electrochemical cell, a plurality of electrochemical cells stacked in series in a bipolar filter crimp configuration, or a plurality of electrical cells stacked in series and electrically connected in a monopolar format. It can consist of chemical cells. The structural element of an electrochemical cell consists of an anode or positive electrode separated from a cathode or negative electrode by an ion conducting electrolyte. When the electrolyte is a liquid, a fine porous separator may be disposed between the anode and the cathode. The positive and negative electrodes are held apart from each other and are housed in a container having a wall that supports and houses the previously identified elements, along with the electrolyte. The container may also have a plurality of input and output ports associated with the supply of reactants and product removal from both the container's anode and container cathode regions.

  The anode and cathode electrodes are made of a substrate material and are coated with a suitable electrocatalyst layer thereon. However, the electrode substrate material may function as the electrocatalyst itself. For many electrochemical processes, the most suitable is to make the electron conductive anode and cathode electrode substrates porous so that liquid or gaseous reactants can reach the electrocatalyst / electrolyte interface, or the base catalyst / electrolyte interface. To allow removal of liquid or gaseous products from the

  Suitable positive electrode substrates that can withstand high positive electrode potentials, highly reactive electrolytes (concentrated water-soluble mineral acids and mineral bases), and highly oxidizing environments are porous titanium, porous titanium suboxide, porous Includes zirconium, and combinations thereof. Porous acidic substrates can be sintered powder or particles, compressed and sintered, or simply compressed irregularly oriented fibers, woven or non-woven or mesh, screens, felt materials, highly perforated metal sheets, or fine pores It can be in the form of an etched metal sheet. For electrochemical ozone generation, suitable anode electrocatalyst layers include α-lead dioxide, β-lead dioxide, boron doped diamond, platinum-tungsten alloys or mixtures, glass fiber, fluorinated graphite, and platinum. .

Suitable cathode electrode substrates or suitable cathode electrode backing materials are stainless steel (especially 304 stainless steel and 316 stainless steel), nickel, nickel-chromium alloy, copper, titanium suboxide, tantalum, hafnium, niobium and zirconium. A porous metal selected from These cathode substrates are porous and may allow for the supply of liquid or gaseous reactants to the cathode electrocatalyst / electrolyte interface or the recovery of liquid or gaseous products from the cathode electrocatalyst / electrolyte interface. Suitable porous cathode substrates include sintered powders or particles, compressed and sintered, or simply compressed irregularly oriented fibers, woven or nonwoven fabrics or meshes, screens, felts, porous metal sheets, or finely etched metal Includes sheets. In the case of electrochemical ozone generation, the most suitable cathode electrode substrate or electrode backing material can be derived from a porous stainless steel material. Preferred cathode electrocatalyst layers are platinum, palladium, gold, iridium, nickel, pyrolytic carbon supported cobalt phthalocyanine, graphite or carbon material, ruthenium oxide, iridium oxide, ruthenium oxide / iridium, ruthenium oxide / iridium / titanium, Includes carbon supported platinum, carbon supported palladium, and mixtures thereof.

  Alternatively, the cathode may be, for example, a gas diffusion cathode consisting of a polytetrafluoroethylene bonded semi-hydrophobic catalyst layer supported on a hydrophobic gas diffusion layer. In one embodiment of the invention, the catalyst layer comprises a proton exchange polymer, a polytetrafluoroethylene polymer, and platinum, palladium, gold, iridium, nickel, pyrolytic carbon supported cobalt phthalocyanine, graphite or carbon material, ruthenium oxide, It consists of an electrocatalyst selected from iridium oxide, ruthenium oxide / iridium, ruthenium oxide / iridium / titanium, carbon supported platinum, carbon supported palladium, and mixtures thereof. The gas diffusion layer has a carbon cloth and carbon paper fiber impregnated with a sintered mass derived from fine carbon powder, and a polytetrafluoroethylene emulsion. This gas diffusion cathode and other gas diffusion cathodes are suitable for air depolarization of the cathode, especially for open cathodes.

  Particularly useful electrolytes in electrochemical cells include aqueous mineral acids, aqueous bases, aqueous salts, or aqueous solutions of salts combined with acids or bases. For the electrochemical production of ozone in the electrolyte cell, it is particularly advantageous to use an electrolyte consisting of water and an acid or salt of a fluoroanion dissolved therein. The fluoroanion electrolyte can generate ozone with a high yield. Fluoroanions, in particular hexafluoro-anions, are particularly preferred.

The particular class of electrolytes suitable for use in accordance with the present invention can be any number of ion exchange polymers, preferably selected from the group consisting of sulfonate, carboxylate, phosphonate, imide, sulfonimide, and sulfonamide groups. Polymers with modified cation exchange groups. Various known cation exchange polymers can be used, including polymers and copolymers such as trifluoroethylene, tetrafluoroethylene, styrene divinylbenzene, α-, β _1- , β ₂ -trifluorostyrene, and the like. And copolymers have cation exchange groups introduced. The polymer electrolyte for use in accordance with the present invention is preferably a highly fluorinated ion exchange polymer having sulfonate ion exchange groups. “Highly fluorinated” means that at least 90% of the total number of monovalent atoms in the polymer is fluorine atoms. Most preferably, the polymer is a perfluorinated sulfonic acid. Solid polymer electrolytes based on perfluorinated cation exchange polymers are most suitable for basic chemical ozone generation. The reason is that only water that is free of dissolved ionic species or suspended inorganic or organic matter need be added to the electrochemical cell. This avoids degradation of electrochemical cell components due to highly reactive electrolytes and contamination of the liquid electrolyte in the generated gaseous ozone.

  It is particularly preferred to utilize an ion exchange polymer that has been reinforced to enhance the integrity and durability of the membrane. That is, an ultra-thin composite membrane having a thickness of less than 50 μm and including a proton exchange polymer incorporated in a stretched porous polytetrafluoroethylene (PTFE) membrane is suitable for use as a polymer electrolyte in the present invention. ing. Another suitable membrane includes a randomly oriented porous substrate of individual fibers and an ion conducting polymer embedded within the porous substrate. Other reinforcing membranes currently available or developed in the future may also be suitable for use in accordance with the present invention.

The proton exchange membrane disposed between the anode and the cathode is made of a polymer material containing sulfonate functional groups on a fluorinated carbon skeleton. Two such materials include “NAFION ™” PEM having an equivalent weight of 1100 grams and Dow experimental PEM (XUS-13204.20) having an equivalent weight of 800 grams. . While “NAFION ™” 105, 115 and 117 each perform well in the present invention, “NAFION ™” 117 is a preferred “NAFION ™” product. However, any sulfonated polymer having a non-fluorinated carbon skeleton is expected to be able to work in accordance with the present invention. Such polymers may include polystyrene sulfonate. In addition, such materials may be coated with a fluorinated material to increase its resistance to chemical attack. Proton exchange membranes made of polymer materials with carboxylate functional groups attached to a fluorinated carbon skeleton are also expected to be operable according to the present invention. Examples are those available from Tokuyama Soda Company under the trade name “NEOSEPT-F”, and from Asahi Glass Company under the trade name “FLEION”. Available, available from Asahi Chemical Industry Company under the trade name "ACIPLEX-S", and Tosho Corporation under the trade name "TOSFLEX IE-SA48" Those available from (Tosoh Corporation). Moreover, perfluorinated bis - sulfonimide _{(CF 3 - [CF 2 SO} 2 NHSO 2 CF 2] n-CF 3), perfluorinated Fosuhon acid, and also the corresponding polymer system based on a carbocation acid, proton exchange according to the invention Works perfectly as a membrane. The Dow Experimental PRM provides much higher performance than the “NAFION ™” PEM material manufactured by duPont. However, “NAFION ™” has been found to be better for impregnating platinum electrodes.

A PEM impregnated gas diffusion electrode can be hot pressed onto at least one side of the purified proton exchange membrane using a Carver hot press to produce a membrane and electrode (M & E) assembly. The hot press procedure involves placing a Suntoitch structure consisting of a PEM and a PEM-impregnated gas diffusion electrode on one or both sides of the PEM, between the platens of the press at about 100 psi (689 kN / m ² ). The platen is preheated to 100 ° C. After the temperature of the platen is raised to a pre-selected range between 125 ° C. to 230 ° ^C., a preselected pressure in the range of 1000psi (6890kN / m 2) ~50000psi (344500kN / m 2), from to 150 seconds 15 seconds Add to membrane and electrode assembly over varying time periods. Hot pressed M & E must be removed from the hot press immediately.

Preferred conditions for the preparation of the M & E assembly consist of a hot press temperature of 160 ° C., a hot press time of 90 seconds, and a hot press pressure in the range of 3000 psi (20700 kN / m ² ) to 14000 (96500 kN / m ² ). I understood it.

  The lead dioxide anode used in the electrolyte cell of the present invention can be prepared by anodic deposition. The choice of anode substrate for depositing lead dioxide is limited. This is because most metals melt when attempting deposition. However, valve metals such as titanium, titanium suboxides (such as those produced by Atravada Limited) under the trade name “EBONEX®”, platinum, tungsten, tantalum, niobium and hafnium. However, it is suitable as a substrate for an anode. When titanium, tungsten, niobium, hafnium or tantalum is utilized as the substrate material, these are first platinum plated to eliminate the passivation problems sometimes encountered in uncoated substrates. The platinization process may include pre-deposition chemical etching of the substrate material.

Carbon in the form of graphite can also be used as the substrate. However, the adhesion of lead dioxide is particularly problematic if the carbon is not completely degassed. To degas the carbon, it is boiled for some time in water and then vacuum dried for several days. When degassed, adhesion is greatly improved against thermal stress. There is no adhesion problem with glass or glassy carbon.

  Platinum is the most convenient substrate material to work with, giving the most uniform deposition and causing no additional problems. Thus, platinum is typically the most suitable substrate material for lead dioxide anodes. However, due to its high cost, the other aforementioned substrate materials are more practical for commercial use.

  In any case, lead dioxide is plated on the substrate in a known plating vessel. The plating vessel consists essentially of lead nitride, sodium perchlorate, copper nitride, and small amounts of sodium fluoride and water. The substrate material is set as the anode in the plating trough whose pH is maintained between 2 and 4. A current density between 10 and 400 milliamperes per square centimeter results in a bright, smooth and adherent lead dioxide deposit. The soot temperature is maintained between 20 ° C. and 70 ° C. throughout the deposition. To perform the deposition, the electrolyte is vigorously stirred and the anode is vibrated quickly and mechanically, resulting in a constant fine particle deposition without pinholes and nodules. When a surfactant is added to the plating solution, the possibility that gas bubbles adhere to the anode surface can be reduced.

Anode electrode substrates and anode electrocatalysts that are particularly suitable for the electrochemical generation of ozone, using either aqueous or solid polymer electrolytes based on cation exchange polymers, are porous coated with a layer of β-lead dioxide Titanium. To enhance the adhesion of β-lead dioxide on the porous titanium substrate, the porous titanium substrate is appropriately cleaned and chemically etched, and then a thin layer of platinum metal or a flash coating is applied on the porous titanium substrate. It has been found that a β-lead dioxide electrocatalyst layer may be electrodeposited immediately thereafter. However, in experiments conducted by the present inventors, when a solid polymer electrolyte based on a cation exchange polymer membrane such as perfluorosulfonic acid is used as an electrolyte, the properties of the porous titanium substrate include electrochemical ozone generation efficiency, And it has been found that there is a significant effect on the lifetime of the electrochemical cell for ozone generation.
Retractable Electrodes The present invention provides means for positioning one or more electrodes in contact with the electrolyte and means for retracting one or more electrodes away from contact with the electrolyte. In a single electrochemical cell device, it is preferred to have only one movable electrode, ie one positioning and retractable electrode and one fixed electrode.

The positioning means and the retracting means may be the same device or different devices. The placement / retraction means is preferably designed to retract in accordance with a given stop condition, which means that the voltage applied between the first electrode and the second electrode is less than 1 volt. Low, expiration of time period, ozone concentration above set ozone concentration, contact pressure less than 5 psi (34.5 kN / m ² ), and combinations thereof. Alternatively, the placement / retraction means may be designed to place one or more electrodes in contact with the electrolyte depending on the given production conditions. The generation conditions are that the voltage applied between the first electrode and the second electrode is higher than 1 volt, the expiration of the time period, the ozone concentration below the set ozone concentration, 5 psi (34.5 kN / m ^2). ) Greater than the contact pressure, and combinations thereof.

When using a lead dioxide anode electrocatalyst, it is very important to prevent the lead dioxide from contacting the acidic environment of the electrolyte while the potential is off. According to the present invention, there are three suitable start and stop modes. First, the anode must be retracted before removing the applied potential, and an appropriate potential must be applied before contacting the anode with the electrolyte. For example, applying a voltage for 30 seconds before the anode initiates contact with the electrolyte and / or applying for 30 seconds after the anode is retracted and separated from contact with the electrolyte. Second, the voltage can be turned off simultaneously with separating the anode and electrolyte. Third, the applied potential is “on”
In this case, contact and retraction of the anode to the electrolyte can act as a switch to switch the current “on” and “off”.

  According to the present invention, it is also useful to provide special start and stop procedures to avoid sudden changes in the power supply. That is, this procedure may include gradually ramping or increasing the power between the current value and the target value. Such a gradual or gradual increase or decrease in power can be used each time the cell is “on” and “off” periodically. For example, the current density through the cell may be increased stepwise from 0.15 amperes per square centimeter several times to eventually reach a final current of 3 amperes per square centimeter. In addition, during the first use of the cell, according to a special “default” profile, such as membrane wetting that must be done during the first use in the cell conditions from cell shipping and storage to full operation It may also be possible to deal with some sort of one-time change. In a preferred embodiment, the power can be adjusted so that the cell voltage stays within a given voltage range, most preferably between 3 volts and 8 volts.

  The positioning means and the retracting means may be active, passive, or a combination of active and passive, but preferably the retracting means is passive and the positioning means is active. As used herein, the term “active” means that a continuous application of external forces (electrical, hydraulic, pneumatic, piezoelectric) is required to ensure the state or position of the device. For example, an electrical solenoid is an active device because it pushes the push rod connected to the solenoid to the desired state only while maintaining power to the solenoid. As used herein, the term “passive” means that the state or position of the device is not maintained without the action of external forces. For example, a wave spring or coil spring is a passive device because, unless an opposing external force overcomes the spring, the push rod connected to the spring is biased to the desired state. As used herein, the term “fail-safe” means a state or location that a device takes in the event of a particular failure, such as a power failure.

  In a preferred embodiment of the invention, the retracting means is passive. To perform passive retraction, a mechanically stored energy device is provided, which maintains the biased electrode toward the retracted state or position so that retraction occurs automatically when the actuation force is released. I have to. The mechanically stored energy device can be a spring, a pressurized fluid container, a weight, and combinations thereof. In this way, the electrode is retracted due to the failure or stoppage of the electrochemical device.

  The placement and retraction of one or more electrodes is generally a reverse movement controlled by a guide member, but the one or more electrodes may follow any of a number of paths. The preferred path is a linear path with a guide member that only allows translational movement of one or more electrodes, but an arcuate path with a guide member that allows only hinged movement of one or more electrodes can also be used. It is. Regardless of the exact direction of the path and the type of guide associated therewith, the operation of the entire working area of the cell is maintained, i.e. in full contact with the PEM, and the working area of any opposing electrode is entirely It is important to arrange one or more electrodes so as to maintain the electrodes facing each other.

The guide member (a plurality of guide members) can be provided in various forms, including one that guides the push rod and one that guides the electrode itself. Furthermore, the guide member may be arranged through or around the electrode or push rod, or may only consist of a rigid connection with the arrangement means. In addition to obtaining electrode and PEM alignment, the guide member preferably limits rotation and lateral movement of the electrode relative to the plane of the PEM. Rotation and lateral movement are not desirable because it may cause physical damage to the PEM or electrocatalyst, but by constantly realigning the electrode and PEM every operating cycle, And any physical variation on the electrocatalyst and the PEM surface is matched to each other as in a conventional cell where the PEM is in a constant compression state. Constant realignment of the electrocatalyst-coated substrate and the PEM every operating cycle is preferred according to the present invention.

The electrolyte used in the electrochemical device of the present invention may be either a liquid electrolyte or a solid electrolyte (also referred to as an ion exchange membrane) such as PEM. Ion exchange membranes are preferred because the liquid electrolyte must be maintained separately from the process water. The electrochemical cell functions with an electrode that simply contacts the membrane, but preferably supports the membrane on one of the electrodes. This support includes securing the membrane to be stationary with respect to one of the electrodes, or bonding or casting the membrane directly to one of the electrodes. One example of a suitable bonding procedure involves heating a fully fluorinated sulfonic acid polymer membrane to about 160 ° C. under a pressure of 300 psi (2067 kN / m ² ), preferably for about 90 seconds. When a lead dioxide anode electrocatalyst is used, an ion exchange membrane is secured to the cathode.

  The cathode is open to the air and there may be no direct supply of water. Such cathodes may be suitable for air depolarization and evaporation treatment of both electroosmotic water and any product water. However, the membrane must be provided with a source of water because it must be kept wet or moist in order to be ion conductive. Optionally, water may be supplied from the anode side as either liquid water or water vapor. Furthermore, water may be supplied as liquid water (without air depolarization) or water vapor so as to back diffuse from the cathode side to the membrane. It is also possible to supply water to the edge of the membrane or other exposed area to “capillary penetrate” or suck water into the membrane. In particular, in applications where sufficient amounts of water are scarce, it is expected that more efficient use of water should be achieved by controlling or limiting the moisture content of the membrane to allow for a decrease in membrane ionic conductivity. The When the amount of water supplied to the membrane is limited, electroosmotic water and generated water at the cathode are absorbed (reversely diffused) by the membrane.

  Although much of the description and drawings of the present invention refer to a single cell, the present invention also includes numerous cell arrays, including both stacked cells and juxtaposed cell arrays. It will be appreciated that both stacked and juxtaposed arrays can be electronically coupled in either parallel or series circuits, depending on the configuration of the electronic conductor and insulator. However, the configuration of a plurality of cells arranged in a side-by-side array may include a plurality of cells in the same plane, a plurality of cells in two or more parallel planes, and a plurality of cells along a curved surface.

  The electrolyte cell can generate gas at any mobility, but the gas concentration preferably includes between about 1 wt% and about 18 wt% ozone in oxygen. A fully passive electrolyte cell for generating ozone is built into equipment that requires ozone for point-of-use water treatment, sterilization, sterilization, decontamination, cleaning, etc. It is most preferable for such a small use point application. Limiting the number of moving parts reduces the initial cost of the device and further reduces the possibility of device failure and the need for maintenance.

  In the following description of the drawings, the same elements are indicated between the drawings if the same numbers are used. Using similar numbers for similar elements means that similar elements have the same general name and function, but similar elements may have more mechanisms in one figure than in the same figure in another figure. It means that it may be less. The intent of using similar numbers is to further clarify these descriptions as common elements of the embodiments appear in each drawing, and even if specific numbers are used, the description Should not be construed as limiting the scope of the invention to any particular mechanism, unless expressly stated otherwise.

  FIG. 2 is an exploded view of a single electrochemical cell 10 that can be arranged to compress two electrodes into contact with an ion exchange membrane. The cell 10 includes a conductive anode substrate 12 having an anode electrocatalyst 14 formed on the surface facing the PEM 16. However, the anode substrate can also function as both a substrate and an electrocatalyst. The conductive cathode substrate 18 has a cathode electrocatalyst 20 formed on the surface facing the PEM 16. However, the cathode substrate can also function as both the substrate and the electrocatalyst. The anode substrate 12, the cathode substrate 18 and the PEM 16 are all fixed by non-conductive bolts 22 and nuts 24. Power supply 26 has a positive terminal 28 and a negative terminal 29, respectively, arranged to be in electronic communication with anode substrate 12 and cathode substrate 18 through electronic conductors. The power supply supplies the potential (volts) necessary to drive the electrochemical process. In one embodiment of the present invention, the cell 10 is immersed in water so that water is fed to the anode electrocatalyst where it is electrolyzed to form an ozone / oxygen mixture and directly into the PEM. Or indirectly supply water to support proton conductivity. Hydrogen gas or other cathode product is formed in the cathode electrocatalyst.

  The anode and cathode substrates are usually conductive metal or ceramic particles or fibers that produce a disc, square or rectangular porous substrate. Examples of substrates include, but are not limited to, woven felt, sintered metal, metal screen, metal mesh, fabric, and the like.

  FIG. 3 is an exploded view of another single electrochemical cell 30 having a separation spring 32, such as a wave spring or wave washer, with the nut 24 removed from the head of the bolt 22. As is the case, when compression is relieved, the anode substrate / electrocatalyst 12, 14 is retracted away from the ion exchange membrane 16. The anode substrate 12 preferably has a recess 34 that receives the corrugated spring compressed during operation and maintains alignment of the corrugated spring with the anode substrate 12 so that the substrate 12 When pressed, contact with the PEM 16 is broken. In applications where it is important to minimize the receding distance, it is advantageous to retract the substrate 12 by an equal distance at any point on the substrate surface, such as by substantially translational movement.

  The retraction or separation distance can be any distance as long as one or more electrodes are moved away from the PEM, but depending on the dimensional tolerance of the actuator and guide member by controlling translational retraction. Thus, very small retraction distances, typically about 1-5 millimeters, are possible, but retreats longer than 5 millimeters and shorter than 1 millimeter are certainly possible. Although the present invention is not particular about any particular separation distance, when referring to separation up to a certain distance, contact between separated components must be avoided, but the dimensional tolerance of the interlocking parts As close as possible to the degree.

  As used herein, the term “retract” refers to movement that results in separation of components. As used herein, the term “actuation” refers to movement that causes contact between components. Neither “retraction” nor “actuation” shall be considered to be implied as to whether pressing or traction was used to obtain separate or contact movement unless explicitly stated to push or pull. . In general, when the drawing shows the retraction obtained by the pressing force, it is natural to recognize that the traction force can be easily adapted to make the same movement. However, as shown in a number of the drawings, when a spring is involved, it is preferred that the spring be in a compressed state rather than a tensioned state, but this is not essential.

  4A is an exploded view of the electrochemical cell stack 40 with a bipolar plate 42 disposed between two cells, such as a pair of cells 30 from FIG. As shown, even a stack of cells can include a passive retraction mechanism (eg, one wave spring 32 per cell) and an active actuation mechanism (eg, a bolt 22 / nut 24 combination). As shown in FIGS. 2-4, the bolt 22 also serves as a guide member that maintains component alignment.

  FIG. 4B is an electrochemical cell stack 41 having two cells 43 with a common cathode substrate 18 and coupled to the negative terminal of the power supply. The two cells 43 are mirror images, but from another perspective, the stack 41 is identical to the stack 40 of FIG. 4A. It is also possible to operate a cell having a common anode and two cathodes.

  FIG. 5A is a schematic side view of an electrochemical device 90 having an anode substrate 12 / electrocatalyst 14 coupled to a push rod 48. The push rod placement is controlled by an electric solenoid actuator 92 to compress the anode substrate 12 / electrocatalyst 14 against the PEM 16 and return spring 46, causing the anode to retract. Since the cathode substrate 18 / cathode electrocatalyst 20 / PEM 16 assembly and solenoid actuator 92 are secured in a fixed relationship, such as by being secured to a common housing 96, the movement of the anode relative to the cathode / PEM simply causes the actuator to move. This can be done by actuating. The cell is shown immersed in water 98, while solenoid 92 is located outside the water. As used in the following example, the controller 94 is connected in an electronic circuit and supplies power to the solenoid 92. The controller 94 can operate the device 90 in any of a number of ways, such as a simple timer that specifies an “on” period and frequency based on various conditions.

  FIG. 5B is a schematic side view of the electrochemical device 90 of FIG. 7A, having a separate deionized water reservoir 91, preferably pre-contained deionized water. The water reservoir 91 is provided in fluid communication with the housing 96 through a conduit 93. Preferably, the water reservoir 91 eliminates the need to incorporate a filtration and deionization device into the apparatus by storing deionized water and supplying high quality water to the apparatus. The water level in the reservoir 91 is controlled within a certain limit. This is because the reservoir 91 adds water to the housing 96 whenever a water level in the housing 96 falls below the height of the inlet conduit 93 so that gas bubbles can enter the housing 91. The head space 95 above the water level allows for phase separation of the ozone / oxygen gas from the water 98, allowing the ozone / oxygen gas to pass through the ozone output 97. The ozone output 97 preferably has a valve (not shown) to regulate gas withdrawal and maintain back pressure.

FIG. 5C is a schematic side view of the electrochemical device 90 of FIG. 5B configured to separate the electrode 12 from contact with the liquid electrolyte 101. This device replaces the ion exchange membrane 16 with the liquid electrolyte 101, and the conduit 93 communicates with the housing 96 and is above the cathode 18, but low enough so that the anode 12 can be retracted from contact with the electrolyte. Except for maintaining the level, it is the same as FIG. 5B. 6A-6F show an example of means that can be actuated or placed so that the electrodes are in contact with the electrolyte. This arrangement means is combined with the spring 46 to passively retract the push rod, when a command is received from the switch-on or the controller 50, gas collector Ru is created moving the push rod 48 solenoid 44 (FIG. 6A), Li retainer 54 and cams 52 which are aligned to actuate the push rod 48 which is disposed between the collar 56 has a spring 46 for passive retraction of the push rod (Fig. 6B), connected to the piston 64 Hydraulic or pneumatic actuator 58 with a push rod 48 that is actuated, including an actuating power fluid supply conduit 60 and a power fluid return conduit 62 that retracts the piston 64 / push rod 48 (FIG. 6C), manual A lead script connected to the power supply 26 via a switch or electronic controller 69. 68, push rod 48 and lead screw motor 66 (FIG. 6D), rack 70 / push rod 48 and pinion 72 (FIG. 6E, motor / power supply not shown), and coupled to push rod 48 , Including a piezoelectric actuator 74 (FIG. 6F) that is activated by the power supply 26 via the switch 50. Other actuation or placement devices and variations of the aforementioned devices are also considered to be within the scope of the present invention.

  7A and 7B are schematic views of an example of a device that latches the push rod 48 in a position to secure an electrode (not shown) in contact with the PEM during application of electricity. In FIG. 7A, push rod 48 includes a fastening notch 76 designed to receive an extension shaft 78 of fastening solenoid 80 upon application of electricity. In the absence of power or in the event of some standby event such as a low cell voltage, the solenoid relaxes and the return spring 81 pulls the shaft out of the notch. The spring 46 retracts the push rod when there is no more applied force 82 applied. In FIG. 7B, the push rod 48 is coupled to an electromagnetic armature 83 that can be selectively secured to an electromagnetic coil latch 84 that is coupled to the power supply 26 via a switch 50. Upon release of the electromagnetic latch 84, the spring 46 retracts the push rod.

  In FIGS. 6A-6F and FIGS. 7A and 7B, in order to effect the movement of the push rod, the elements that cause and prevent the movement of the push rod are secured to the housing or other securing structure of the electrochemical device. It will be appreciated.

  FIG. 8 is a schematic side view of an experimental electrochemical cell 100 setup, with an adjustable load such as bolt 102 and spring 104, and a load that measures this load and displays or records the load with meter 108. It has a cell 106. Ozone generation efficiency can be related as a function of compressive force between the electrode and the PEM. It is the compressive force per unit area that is considered important for optimal cell performance.

  FIG. 9 is a schematic side view of the electrochemical device 110 with a water reservoir or housing 112 and a fluid at the push rod end 48a having a sealing member, such as a diaphragm 114, coupled to the placement member 116. Allows sealing movement. Placement member 116 is isolated from push rod end 48b coupled to water and anode 12. Optionally, the sealing member may be a piston ring, a shaft seal, or the like.

  As shown, the cathode 18 and the PEM 16 are fixedly secured to the floor 118 and the inner wall 120 of the housing 112 at the top and bottom surfaces. The anode 12 is maintained in alignment with the cathode / PEM by the guide member. The guide member includes surfaces 122 and 124 and is preferably on a circumference around the anode 12. The apparatus 110 is also shown to have an anode chamber 126 that is isolated from the anode chamber 128. One effect of this isolation is the separation of the anode gas from the cathode gas. However, as a result of isolation and electroosmotic flow of water from the anode to the cathode, there is a conduit 129 in the device 110 that allows the water to circulate from the cathode chamber 128 to the anode chamber 126 without mixing gases. This is effective.

  Optionally, the present invention provides a unique gas decomposition system capable of decomposing waste hydrogen and / or ozone. Hydrogen is mixed with oxygen (or air) and transferred to a hydrogenolysis catalyst that generates heat. The hot gas containing excess oxygen is then combined with the waste ozone and transferred to the downstream ozonolysis catalyst. Since the ozone generator continuously produces hydrogen, the heat from the hydrogen decomposition maintains the ozone catalyst at a high temperature, further activates the catalyst, and continuously dries the ozone decomposition product. Thus, the ozonolysis catalyst is maintained in the ozonolysis preparation state. Alternatively, hydrogenolysis can provide high temperature heat, which can be used for other unrelated processes, home hot water heating, and the like.

FIG. 10A is a schematic side view of another electrochemical cell or device 130 having a hydraulically actuated anode. In this case, the power fluid can be process water or another fluid. The anode 12 is coupled to a push rod 48 that has a piston 132 at the opposite end. Piston 132 is actuated by fluid entering piston head space 134;
The return spring 136 is compressed and the anode is placed in compression contact with the PEM 16. The apparatus has an optional diaphragm 138 attached around the push rod 48 to maintain process water isolation. Process water enters through passage 140 and exits with gas generated from the power fluid through passage 142.

  The anode 18 is fixed together with the PEM 16 fixed to the anode. It should be noted that there is no cathode chamber or reservoir around the cathode and the cathode is open to air, which can also be referred to as “drying”. An open or exposed cathode may be suitable for air depolarization and evaporative disposal of both electroosmotic water and any product water. Therefore, there is no direct water supply to the cathode.

  FIG. 10B is a schematic side view of two electrochemical cells / devices according to FIG. 10A and a common cathode in between. The common cathode 18 is coupled to the power supply 26 as in FIG. 4B. However, the apparatus of FIG. 10B has two movable anodes 12 coupled to two arrangements and retracting means. This means operates similarly to the individual means of FIG. 10A. The two means can be operated with the same or different power fluids and can also be activated and retracted at the same or different times. It is conceivable that the two movable electrodes have different characteristics from each other. The characteristics are, for example, catalyst loading, amount of working area, type or concentration of product produced. Optionally, the two electrodes are operated independently, one anode is used to produce an 18 wt% ozone solution and disinfect the cooktop, and the other anode is used to produce 2 wt% ozone and the skin. It is also possible to provide a solution optimized for different specifications, such as used to clean the burns.

  FIG. 11 is a schematic side view of another electrochemical device 150, a process water reservoir 152 and a pump that delivers process water 153 to the electrochemical cells (anode substrate 12, PEM 16, cathode substrate 18) and internal hydraulic actuators. 154. The hydraulic actuator is similar to that of FIG. 10 except that the piston 132 is operated with process water 153. The apparatus also includes, among other things, a filter 154 that removes particles, dissolved organic compounds, and heavy metals (also acting as an ozone decomposition catalyst), preferably a carbon filter, a flow controller 156 (such as a flow restriction orifice), and process water 153. A deionized resin bed 158 to remove dissolved ions, a delead unit 160 (such as a column of zeolite, alumina, silica lead ions or other materials known to bind or adsorb colloidal lead species), a venturi 162, And a back pressure control orifice. It should be appreciated that the order of the filter 154, flow controller 156, and deionized resin bed 158 is not constrained.

  In operation, water 153 from reservoir 152 is supplied to the inlet of pump 154 through reservoir discharge conduit 165. Pump discharge conduit 166 supplies high pressure water and delivers it to piston powered fluid chamber 134 or returns to reservoir 152 through venturi 162 and back pressure control orifice 164. The high pressure process water activates the piston as in FIG. 10, but the process water passes through the carbon filter, flow controller, and deionized resin bed in its path to the anode chamber. The deionized water supports electrolysis at the anode 12 and proton conductivity through the PEM 16 to the cathode 18. The electroosmotic water that reaches the cathode 19 can be reused or discarded (i.e., discarded to the drain or evaporated). However, water that is not used at the anode is ozonated and the water leaks out of the anode chamber along with the ozone / oxygen gas flow through the exhaust conduit 167 and passes through the delead unit 160. Downstream of the delead unit 160, the ozonated water and ozone / oxygen gas streams are drawn into the venturi and circulated to the reservoir 152 to increase the ozone concentration.

  Activation of an electrochemical device, such as device 150 of FIG. 11, can proceed in a number of ways, including (1) introducing process water into a water reservoir, and (2) first electrode and second Most preferred is the order described, including applying a voltage between the electrodes, (3) turning on the water pump, and (4) placing the movable electrode in contact with the electrolyte.

  FIG. 12 is a schematic side view of the electrochemical device 150 of FIG. 11 with the carbon filter 154 and deionization bed 158 positions transferred to the reservoir discharge conduit 165. A flow control orifice 156 is also left between the power fluid chamber 134 and the anode chamber to maintain or enhance the differential pressure acting on the piston 132. It is also shown that the return spring 136 can be placed in a pulled state.

  13A-13C are schematic views of a deionized bed configured to externally display color changes to the individual users of the device, indicating the extent to which the bed has been depleted. Suitable deionized materials that change color upon ion exchange include MBD-12 and MBD-13 self-indicating mixed bed resins (Resintech, Inc., Cherry Hill, NJ). Available), and IONAC NM-65 directed mixed bed resin (available from Symbron Chemicals Inc., Birmingham, NJ). Such a color change is believed to be due to the presence of an indicator dye in, on or around the deionized material. Many methods are possible to place the deionized bed adjacent to the transparent viewing window, but the deionized bed has an elongated column with a high aspect ratio (ie, several times the width). It is preferable to form. In this way, the deionized material closest to the column inlet performs ion exchange first, and less downstream material is used until the upstream material is completely replaced. Thus, the region of the column that performs deionization at any one time is clearly distinguished and this region moves along the length of the column as the material is used. Since the deionized material used has a color change indication, the color change also moves along the column. A plurality of segments of the column are separated in series, and the column is configured so that they pass through the viewing window, so that a display can be provided and the state of use can be quickly indicated. Preferably, the viewing window is provided with a “deionized bed exchange” command adjacent to one of the latter column segments so that it can be seen through the viewing window. Although the foregoing configuration has been described with reference to a deionization bed, a deleading unit can also be prepared using the same configuration, color indication, and viewing window.

  In FIG. 13A, a side view shows a deionization column 170 arranged in an elongated serpentine pattern, which includes an inlet 172, an outlet 174, a deionization material 176 disposed therebetween, and one end of the serpentine. A viewing window 178 adjacent to. FIG. 13B is an end view of the column 170 showing the display formed by the viewing window. For example, if an individual user consumes 2/5 of the current column and replaces the column when 4/5 of the column is consumed and does not prevent the passage of ions, the ion or ion in the electrolyte or PEM May quickly reach you and may damage it. Although the display is shown as a segmented array of viewing windows, it is equally suitable to have a continuous viewing window along the edges. FIG. 13C is a side view of another column arranged in a spiral, with an inlet 172, outlet 174, deionized material 176, and a viewing window 178 spanning the entire downstream segment of the column. Here, the segment represents an equal fraction of the column, but it is still valid if the display indicates to the individual user when to replace the column with a new column.

FIG. 14 is a schematic side view of an electrochemical device that uses deionized water from reservoir 191 instead of using process water from reservoir 152. Like FIG. 7B and FIG. 7C, by using the pre-contained deionized water 91, the possibility of contaminating the anode and the PEM is eliminated, and a filtration and deionization device is not required in the apparatus. Here, the process water 153 is pressurized by the pump 154 and conversely delivered to the piston 132 to actuate the movable electrode and pass through the venturi 162 to draw ozone gas into the process water. Preferably, the anode chamber is provided with a water conduit 93 so that the deionized water level is always below the ozone discharge port 168. Also, the anode chamber has sufficient headspace to allow phase separation of ozone / oxygen gas from the water so that only the gas phase is drawn into the venturi 162 through the port 169. A seal or diaphragm is provided around the push rod 48 to prevent pressurized process fluid acting on the piston from entering the anode chamber. As shown, the diaphragm 171 defines the upper limit of the anode chamber.

18A-18C are perspective views of retractable electrodes coupled to the shaft, with the electrodes being modified to improve current distribution and collection across the electrode surface. FIG. 18A shows an electrode 200 that preferably has a set of preferably metal conductive ribs 206. Ribs 206 are formed in a radiating pattern on the back surface of the anode substrate 204 to improve the distribution and collection of current from the conductive shaft 202 across the surface of the electrode substrate 204. This design improves current distribution without blocking the surface area of the anode substrate or increasing the thickness of the porous anode substrate. FIG. 18B shows an electrode 210 having a set of fully embedded conductive members 208 arranged radially from the shaft 202. In both FIG. 18A and FIG. 18B, the conductive members 206, 208 are formed in the porous substrate 204. Preferably, the conductive members are placed in a metal powder and crimped together under considerable pressure to form a “green body”. Next, the substrate is transferred to a furnace, and the substrate 204 is sintered. FIG. 18C shows the electrode 220, but the conical substrate 224 coupled to the shaft 222 is less preferred than that described above. Increased substrate thickness also increases current distribution and collection across the anode surface. Unfortunately, the increase in thickness also increases the distance that the anode reactant and product must diffuse.
Example 1
Porous titanium substrate, ie, titanium woven fabric piece (150 × 150 per inch, transparent, 0.0027 ″ (0.0686 mm) wire diameter, oblique weave, 35.4% open area, unique wire wave (Unique) Wire Weave, Hillside, NJ07205), followed by electroplating of β-lead dioxide. A plurality of these β-lead dioxide coated titanium cloths were made into commercially available proton exchange polymer membranes (Delaware). Electricity incorporated with EI du Pont de Nemours and Company, Wilmington, DE 1989, Wilmington, USA, under the trade name NAFION® Used in chemical cells This is a perfluorosulfonic acid polymer electrode, and in some cases, a titanium cloth coated with β-lead dioxide is simply applied to one side of the proton exchange membrane sample by means of fastening the end plates of the electrochemical cell together. In another case, a titanium cloth coated with β-lead dioxide was hot-pressed on one side of a similar sample of a proton exchange membrane, where it was preheated to 100 ° C. A sandwich structure consisting of a cation exchange membrane , β-lead dioxide- coated titanium cloth anode electrode, and a platinum-indicating carbon catalyst carbon cloth gas diffusion electrode on either side of the membrane , between hot press platens. Place and crimp at about 100 psi (689 kN / m ² ) Next, raise the platen temperature to 120 ° C. and apply 2500 psi (17237 kN / m ² ) pressure for 90 seconds.

When testing the performance of an electrochemical cell comprising a β-lead dioxide coated titanium cloth electrode bonded to a cation exchange polymer membrane by either method, the ozone gas content in the generated ozone / oxygen gas flow is the initial value. From a high 12-15 wt% to a value of about 1-2 wt% was found to decrease in about 12-24 hours. In addition, the cell voltage also decreased from an initial high value of about 4-6 volts to a value of about 1-2 volts. In addition, when removing a tested electrochemical cell containing a β-lead dioxide coated titanium cloth as the anode substrate / anode electrolyte material, in the region of the proton exchange polymer membrane in contact with the β-lead dioxide electrolyte layer, Milky white liquid material was covered. The surface of the proton exchange polymer membrane in contact with the platinum-supported carbon anode electrolyte layer exhibited dendritic or fractal growth of the material within the membrane.

  Although the nature of these materials on the surface of the proton exchange polymer membrane was not determined, the following process was performed when inspecting these electrochemical cells for electrochemical ozone generation. The individual strands that make up each titanium woven fabric sample were electroplated with lead dioxide over the entire circumference of the cylindrical strands. However, when the β-lead dioxide-coated titanium cloth sample is bonded to the surface of the proton exchange membrane sample, the surface of the β-lead dioxide electrolyte layer, whether mechanically crimped when the end plate is fastened or by thermal pressure, Only a portion of the entire area was in contact with and embedded in the proton exchange polymer membrane material.

When an electrochemical cell containing such an anode electrode substrate / electrolyte layer is operated, a part of the β-lead dioxide electrolyte layer not in contact with the proton exchange polymer membrane is present on the anode surface under electrochemical ozone generation conditions. Slowly dissolved due to the presence of a highly acidic environment. A part of the dissolved β-lead dioxide was transferred to the surface of the cathode through the cation exchange polymer membrane in the form of pb ²⁺ cation and applied with an electric field, and was reduced to metal lead atoms. . Gradually, the accumulation of lead metal atoms resulted in dendritic growth of electrovolume lead metal from the surface of the cathode through the proton conducting channel. Proton conducting channels are known to exist in the proton exchange polymer membrane up to the surface of the anode. Finally, the proton exchange polymer membrane became a mixed ion / electron conductor as the time of electrochemical ozone generation increased, and the electron conduction characteristics improved. This is the reason why the cell voltage decreases as the electrolysis time increases.

Since the titanium woven fabric is composed of fine cylindrical titanium wires, the subsequent contact of these β-lead dioxide coated titanium wires with the surface of the proton exchange polymer membrane results in local contact points. It was to be embedded inside the surface of the membrane, particularly at points corresponding to the overlap of the wire mesh. Thus, the average current density applied to the electrochemical cells when performing the various tests is 1 Acm ⁻² on average, but the local actual current density applied to these contact points is about 5-10 Acm. ^The possibility of becoming ^-2 is very high. The combination of the heating effect (with high local current density) and the highly oxidizing environment (with ozone generation) resulted in partial degradation of the proton exchange membrane. This is intended to be retained by observation of milky white liquid material on the surface of the proton exchange polymer membrane in contact with the β-anode lead dioxide electrolyte layer. In all cases, to perform an electrical test with a β-lead dioxide coated titanium cloth anode, deionized water is used, circulated between the reservoir and the electrical science cell, and the water temperature is 30 ± 3 ° C. Maintained.
Example 2
Another type of porous titanium substrate, ie sintered porous titanium substrate, regular shaped titanium powder (eg spheres) or irregularly shaped titanium particles at high temperature and pressure under inert gas Sintered formed in environment and used. These are respectively Astro Met Inc. Cincinati, OH 45215 (100-80 / 120 and 100-45 / 60; 5.5 "x 11" x 0.050 "(Cincinnati, Ohio) 140 × 1.27 mm) sheets) and Mott Corporation, Farmington, CT06032, Farmington, Connecticut (Mott Corporation, CT06032) (Mott 40 microns and Mott 20 microns). Subsequently, β-lead dioxide was electroplated as described above to obtain a titanium cloth sample.When the end plates of the electrochemistry cell were fastened together, the β-lead dioxide-coated sintered porous titanium substrate was Mechanically pressed against one side of a sample of an ion exchange polymer membrane (NAFION®), these tests were performed under the same conditions as used for the β-lead dioxide coated titanium cloth anode electrode substrate. The thickness of the porous titanium substrates is in the range of 0.040 ″ to 0.075 ″ (1.02 × 1.91 mm) and these substrates are observed to have very flat parallel surfaces. Β-lead dioxide was deposited on only one surface of the sintered porous titanium substrate to form a uniform film covering the entire surface of each substrate.

When the β-lead dioxide coated sintered porous titanium substrate was tested for electrochemical ozone generation, the electrochemical cell containing these anode substrates / electrolyte layers was left compressed and from an external DC power source. It has been found that if an applied current density of 1.0 to 1.6 Acm ⁻² is applied to the electrode, ozone can be generated at a high concentration of about 12 to 15 wt%, possibly in an indefinite period of time. In deionized water flowing between the electrochemical cell and the reservoir at a temperature of 30 ± 3 ° C., the cell voltage was observed to be 3.5-5.5V. The unexpected result that a high weight percentage of ozone was continuously produced over a long period of time is attributed to the fact that the surface of the sintered porous titanium substrate was flat. Thus, the β-lead dioxide layer on such a surface is also flat so that all of the exposed surface area of the β-lead dioxide layer is in contact with the surface of the proton exchange polymer membrane and under electrochemical operating conditions, A voltage higher than 3.0 V was applied between the β-lead dioxide / proton exchange polymer membrane sea level. As shown in FIG. 1, in such a situation, β-lead dioxide should stabilize indefinitely.
Example 3
On the β-lead dioxide-coated sintered porous titanium substrate, an “on” / “off” operation was performed at a large number of applied current densities to gradually decrease the ozone current efficiency. For coated substrates that are continuously maintained in compression with the proton exchange polymer membrane, the current density is "on" four times both when the applied current density is "on" and when the applied current density is "off". / Ozone was generated at a current density of 14.5 (corresponding to a concentration of 14.5 wt%) in the initial state due to the effect on the ozone current efficiency for the electrochemical cell when “off”. This is illustrated in FIGS. 17A and 17B. It was further observed that the dramatic effect on the ozone current efficiency of “on” / “off” the applied current density was more pronounced for electrodes with low β-lead dioxide electrocatalytic loading. is there. For example, when the β-lead dioxide load is 5 to 10 mg cm ⁻² , the ozone generation capacity of the electrochemical cell is reduced from 10 to 12 wt% to less than 2 wt% by turning on / off the applied current density. . For electrodes with a β-lead dioxide load of 80 mg cm ⁻² , an ozone generation capacity of about 5 wt% was observed after the applied current density was “on” / “off” nine times.

The decrease in ozone generation capability as a result of the time interval during which no current density is applied to the electrodes is suggested by the data shown in FIG. This figure shows that in a lead-water system at low electrode potential, that is, when the anodic current does not pass through the electrode / electrolyte sea surface, Pb ²⁺ ions are the most stable species in acidic environments. Leaving the β-lead dioxide coated sintered porous titanium substrate in contact with the acidic proton exchange polymer membrane without passing current through the electrochemical cell causes degradation of the β-lead dioxide electrolyte layer, followed by When the current is reapplied between the β-lead dioxide coated anode and cathode, its ability to generate ozone gas is impaired, i.e. reduced.

Under conditions no electric field is applied, i.e., when the current density applied to the electrodes to "off", dissolution / precipitation process with PbO 2 _/ Pb ²⁺ is generated in the β- lead dioxide / proton exchange polymer membrane interface There is a high possibility of doing. Unlike the situation described above for the β-lead dioxide coated titanium cloth, when the electric field is not applied while the current is “off”, Pb ²⁺ ions move into the proton conducting polymer membrane toward the cathode surface. There is no driving force to do.
Example 4
In an experimental setup, four electrochemical cells were prepared, and by disconnecting the proton conducting polymer membrane and the β-lead dioxide coated porous anode substrate during the time when no current was flowing between the anode and the cathode, Such electrochemical cells have a significantly longer lifetime, maintaining a high ozone production rate when the applied current density is again applied to the electrode after the current is turned “off”. However, this solution can only be applied to a porous anode substrate having a flat surface, as described above in the second example involving the use of a sintered porous titanium substrate. The proposed solution is the basis of the invention disclosed in this patent application, where the electrocatalyst-coated porous substrate and the membrane are in contact with the proton exchange polymer membrane when compressed in an electrochemical cell. It is not effective in the case of a porous anode substrate in which the surface area of the layer of the lead anode electrocatalyst, that is, the region of the surface of the layer is only a part.

  A porous anode substrate that is not effective is relatively thin (thickness less than 0.010 ″ (0.254 mm)) and a layer of β-lead dioxide electrocatalyst material on the front or first side of the thin wiring The entire periphery has large pore walls that are easy to reach water and on the back or surface 2. A representative example of such a porous substrate is described above in the first example, Other ineffective porous substrates have involved the use of titanium woven fabrics, including non-woven fabrics, woven or non-woven meshes, screens, perforated thin metal sheets, or thin metal sheets with finely etched holes. Lead dioxide electrocatalyst layer in contact with proton exchange polymer membrane, woven or non-woven, woven or non-woven mesh, screen, perforated thin metal sheet, or thin gold with finely etched holes When the plated porous anode substrate and the film sample are deposited in the compressed state in the electrochemical cell by depositing only on the surface of the exposed surface region of the metal sheet, the divided area or part of the surface, and the second embodiment, The proposed solution is valid for these substrates as if for a sintered porous metal or ceramic substrate as described in.

  an apparatus that allows the β-lead dioxide coated porous anode substrate to be retracted, disconnected from contact with the proton conducting polymer membrane, and subsequently contacted again with the proton conducting polymer membrane; The method was prepared according to FIG. That is, the apparatus and method of the present invention retracts all of the exposed surface area of the β-lead dioxide film on the porous anode substrate during current “off” to contact the proton exchange polymer membrane in the electrochemical cell. Must be able to break. Similarly, the apparatus and method of the present invention ensures that all exposed areas of the β-lead dioxide coating on the porous stamped substrate in the electrochemical cell are in contact with the proton exchange polymer membrane sample during the current “on”. Must be able to place.

  The cathode and PEM are fixed, and only the porous titanium anode substrate and lead dioxide electrocatalyst are coupled to the end of an electrically operated solenoid actuator. The solenoid actuator pushes the anode substrate / electrocatalyst into contact with the PEM in a compressed state, and a pair of springs raise the anode substrate / electrocatalyst away from the PEM. A controller was used to control each of the four electromechanical cells at a given period and operating frequency. Each of the cells was operated without switching the power off. However, when the cell was turned “off”, the anode was retracted to break contact with the PEM / anode. This is because deionized water without ionic conductivity effectively forms an open circuit. Cell # 1 was operated on a 1.5 minute “on” and 1.5 minute “off” cycle. Cell # 2 was operated on a 25 minute “on” and 10 minute “off” cycle. Cell # 3 was operated with a cycle of 25 minutes “on” and 2 hours “off”. Cell # 4 was operated on a 26 minute “on” and 24 hour “off” cycle. When operating the control cell, the power was switched off while the anode was retracted, but the results showed that there was no significant difference in performance compared to the cell with continuous power.

When measuring the concentration of ozone gas produced by each of the four electrochemical cells, UV light from ozone dissolved in deionized water around the cell was used using an Ocean Optics UV absorption system and software. The absorption of was monitored. FIGS. 15A-15D show the absorbance measured periodically after a number of operating cycles have been performed on cells 1-4. The sign in each figure indicates the number of operating cycles in which the dissolved ozone concentration was tested. For each test, the figure plots the percentage absorbance as a function of time in seconds over a period of about 1500 seconds. The charts in FIGS. 15A to 15D show that in cells 1 to 4, despite the operation cycle of 62218 times, 63468 times, 4826 times, and 1412 times, the drop that occurred in ozone generation is very small. Show.
Example 5
An electrochemical cell was prepared according to FIG. 8, and the cell voltage when the compression between the electrodes was changed between about 10 psi to about 260 psi (69 to 1792 kN / m ² ) was measured. FIG. 16 is a graph of cell voltage obtained as a function of pressure in psi for an electrochemical cell. This graph shows that the cell voltage drops sharply when the pressure is increased to about 50 psi (345 kN / m ² ). At a pressure of about 50 psi (345 kN / m ² ), the cell voltage dropped very little even if the pressure was further increased.

  While the foregoing description is directed to preferred embodiments of the invention, other embodiments of the invention may be devised without departing from the basic scope thereof, the scope of which is claimed. It shall be determined by

The potential-pH equilibrium diagram of lead-water system at 25 ° C. A single electrochemical cell that can be placed in contact with the ion exchange membrane by compressing the electrode. Another single electrochemical cell having a wave spring that retracts the electrode from the ion exchange membrane in the absence of compression. 4 is an electrochemical cell stack having a bipolar plate between the two cells of FIG. An electrochemical cell stack having two cells with a common cathode. FIG. 3 is a schematic side view of an electrochemical cell having an anode coupled to a push rod and an electrosolenoid actuator having a return spring to control the positioning of the push rod. FIG. 5B is a schematic side view of the electrochemical cell of FIG. 5A with a separate deionized water reservoir. FIG. 5B is a schematic side view of the electrochemical cell of FIG. 5B configured to retract the electrode from contact with the liquid electrolyte. FIG. 3 is an example of a means by which an electrode can be actuated or placed in contact with an electrolyte, showing a means including an electrical solenoid with a spring retracted. FIG. 4 is an example of a means by which an electrode can be actuated or placed in contact with an electrolyte, showing a means including a cam with a retracted spring. FIG. 2 is a diagram showing an example of a means that can actuate or place an electrode in contact with an electrolyte, including a hydraulic or pneumatic actuator. FIG. 2 is a diagram showing a means including a lead screw, which is an example of a means by which an electrode can be actuated or placed in contact with an electrolyte. FIG. 4 is an example of a means by which an electrode can be actuated or placed in contact with an electrolyte, showing a means including a rack and a pinion. FIG. 4 is a diagram illustrating a piezoelectric actuator, which is an example of a means by which an electrode can be actuated or placed in contact with an electrolyte. The figure which shows an example of a means which fastens a push rod during application of electricity, and contacts and fixes an electrode to PEM. The figure which shows an example of a means which fastens a push rod during application of electricity, and contacts and fixes an electrode to PEM. FIG. 4 is a schematic side view of an experimental electrochemical cell setup with an adjustable load and a load cell that relates cell operation as a function of compressive force between the electrode and the PEM. 1 is a schematic side view of an electrochemical device having a water reservoir and a diaphragm that allows sealing movement of the push rod. FIG. FIG. 3 is a schematic side view of an alternative electrochemical device having a hydraulically actuated anode. FIG. 10B is a schematic side view of an apparatus according to FIG. 10A that has two electrochemical cells / apparatus with a common cathode therebetween. FIG. 4 is a schematic side view of an alternative electrochemical device having a process water reservoir and a pump that delivers process water to an electrochemical cell and an integrated hydraulic actuator. FIG. 12 is a schematic side view of the electrochemical device of FIG. 11 with a carbon filter and deionization bed transferred to the pump inlet. FIG. 3 is a schematic diagram of a deionized bed configured to display a color change indicating how much the bed has been spent. FIG. 3 is a schematic diagram of a deionized bed configured to display a color change indicating how much the bed has been spent. FIG. 3 is a schematic diagram of a deionized bed configured to display a color change indicating how much the bed has been spent. 1 is a schematic side view of an electrochemical device having a separate deionized water reservoir in fluid communication with an anode. FIG. FIG. 8 is a graph of absorbance as a function of time in seconds for an electrochemical cell constructed according to FIG. 7 and operated over a number of repeated cycles. FIG. 8 is a graph of absorbance as a function of time in seconds for an electrochemical cell constructed according to FIG. 7 and operated over a number of repeated cycles. FIG. 8 is a graph of absorbance as a function of time in seconds for an electrochemical cell constructed according to FIG. 7 and operated over a number of repeated cycles. FIG. 8 is a graph of absorbance as a function of time in seconds for an electrochemical cell constructed according to FIG. 7 and operated over a number of repeated cycles. 9 is a graph of cell voltage as a function of pressure in psi for the electrochemical cell of FIG. A graph of the ozone current efficiency in percentage as a function of the period during which the ozone generator is cyclically warmed and turned off. A graph of the ozone current efficiency in percentage as a function of the period during which the ozone generator is cyclically warmed and turned off. FIG. 5 is a diagram of a retractable electrode coupled to a shaft, modified to improve current distribution and collection at the electrode surface. FIG. 5 is a diagram of a retractable electrode coupled to a shaft, modified to improve current distribution and collection at the electrode surface. FIG. 5 is a diagram of a retractable electrode coupled to a shaft, modified to improve current distribution and collection at the electrode surface.

Claims (20)

An electrochemical cell comprising: a cathode electrode; an anode electrode; an acidic electrolyte disposed between the anode electrode and the cathode electrode; and a power source that applies a voltage between the anode electrode and the cathode electrode. The anode electrode is in contact with the acid electrolyte and the anode electrode in response to one or more predetermined standby states; the lead dioxide electrocatalyst is in contact with the electrolyte; from the position, possess a retraction mechanism for retracting a retracted position where the lead dioxide electrocatalyst is separated from the electrolyte, the electrochemical cell, the retracted position the anode electrode in response to one or more production conditions Further comprising an actuator that is moved back to an initial position and the retracting mechanism is constituted by a passive device that biases the anode electrode away from the electrolyte, Based on the power from the overcoming the biasing action of the passive device, an electrochemical cell, characterized in that constituted by the active mechanism is operable to contact with the electrolyte by moving the anode electrode. The cell according to claim 1, wherein the lead dioxide electrocatalyst is β-lead dioxide, α-lead dioxide, or a combination thereof. The cell according to claim 1, wherein the acidic electrolyte is a proton exchange membrane. The cell according to claim 1, wherein the acidic electrolyte is an aqueous solution of a dissolved inorganic acid, a dissolved organic acid, or a mixture thereof. The cell of claim 1, wherein the one or more standby states are:
The voltage applied between the anode electrode and the cathode electrode is less than 1 volt, the operation time period of the cell has expired, and the ozone concentration is higher than the set ozone concentration in the cell. A cell selected from the absence of an anodic oxygen / ozone generation reaction and no current flowing through the cell. 4. The cell of claim 3, wherein the one or more standby states are such that the contact pressure of the anode electrode with the proton exchange membrane is 10 psig (69 kN / m ² ) A cell that contains less than. The cell of claim 1, wherein the one or more generation states are:
The voltage applied between the first electrode and the second electrode is higher than 1 volt, a certain period of time has expired from the end of the operation of the cell, and the ozone concentration is the set ozone concentration in the cell. A cell that is selected from being lower than. The cell according to claim 3, wherein the generation condition is that a contact pressure of the anode electrode with the electrolyte is 10 psig (69 kN / m). ² ), Including exceeding. 2. The cell according to claim 1, wherein the active mechanism receives power from the power source, and the power source is connected to the active power source when the power source is connected to apply a voltage between the anode electrode and the cathode electrode. A cell that supplies power to the mechanism. The cell of claim 1, wherein the lead dioxide electrocatalyst retains its β-lead dioxide crystal form. Ozone in an electrochemical cell having a cathode electrode, an anode electrode, an acidic electrolyte disposed between the anode electrode and the cathode electrode, and a voltage source coupled between the anode electrode and the cathode electrode Wherein the anode electrode comprises a retraction mechanism constituted by a passive device that biases the anode electrode away from the electrolyte, and the electrochemical cell is based on power from a power source, And further comprising an actuator constituted by an active mechanism operable to overcome the biasing action of the passive device to move the anode electrode into contact with the electrolyte, the method comprising the anode electrode and the cathode electrode And applying a voltage between the active electrode and the active mechanism to retract the anode electrode away from the electrolyte. Actively moving the anode electrode to an operating position in contact with the electrolyte and turning on the voltage source prior to or simultaneously with engagement of the anode with the electrolyte, the method comprising: The method further comprising the step of passively retracting the anode electrode by the action of the passive device to break contact with the acidic electrolyte immediately before or simultaneously with turning off the voltage source. 12. The method of claim 11, wherein the step of retracting the anode electrode and disconnecting from the acidic electrolyte is performed in response to sensing one or more predetermined standby conditions. The method of claim 12, wherein the one or more waiting conditions are:
  The voltage applied between the anode electrode and the cathode electrode is less than 1 volt, the operation time period of the cell has expired, and the ozone concentration is higher than the set ozone concentration in the cell. A method selected from the fact that no anodic oxygen / ozone generation reaction has occurred and no current is flowing through the cell. 12. The method of claim 11, wherein the acidic electrolyte is a proton exchange membrane and the one or more standby conditions are such that the contact pressure of the anode electrode with the proton exchange membrane is 10 psig (69 kN / m ² A method comprising: 15. The method according to any one of claims 11 to 14, wherein the contact engagement of the anode electrode with the electrolyte is performed in response to sensing one or more production conditions. 16. The method of claim 15, wherein the one or more generation conditions are:
  The voltage applied between the anode electrode and the cathode electrode is higher than 1 volt, a certain period of time has expired from the end of the operation of the cell, and the ozone concentration is lower than the set ozone concentration in the cell. A method selected from being low. An electrochemical cell comprising: a cathode electrode; an anode electrode; an acidic electrolyte disposed between the anode electrode and the cathode electrode; and a power source that applies a voltage between the anode electrode and the cathode electrode. The device further moves the anode electrode overcoming the biasing action of the passive mechanism based on the passive mechanism that biases the anode electrode away from the electrolyte and the power from the power source. An electrochemical cell comprising an active mechanism operable to contact the electrolyte. 18. An electrochemical cell according to claim 17, wherein the active mechanism is adapted to be activated when the power source is connected and a voltage is applied between the electrodes. 19. The electrochemical cell according to claim 17 or 18, wherein the passive device retracts the anode electrode, breaks contact with the electrolyte, and shuts off the circuit incorporating the cell, thereby waiting the cell. An electrochemical cell characterized in that. 20. The electrochemical cell according to any one of claims 17 to 19, wherein the passive device retracts the anode electrode in contact with the electrolyte in response to sensing one or more predetermined standby conditions. An electrochemical cell characterized by cutting off.

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